The present invention relates to an IC card, and more particularly, it relates to a technique to control OS activation suitable to an IC card applicable to a plurality of data transfer methods and including a plurality of operating systems (OSs), and in particular, suitable to a contactless IC card.
IC cards composed of IC chips having nonvolatile memories have recently been widely spread as electric money, ID cards, commuting tickets and phonecards. This type of IC cards employ, depending upon their use environments and systems, various data transfer methods and management methods for data in their memories different in accordance with their intended uses. Therefore, a user should use IC cards according to the standards necessary for the respective uses and hence should unavoidably possess a plurality of IC cards.
In order to solve this problem, a conventional technique in which data demodulating means corresponding to a plurality of data transfer methods are provided in an IC chip built in one IC card so as to select an appropriate demodulated signal by using a selector has been proposed (for example, see Japanese Laid-Open Patent Publication No. 2000-172806 (pp. 2–5 and FIG. 4)). In this conventional technique, one IC card can cope with the Type A method and the Type B method defined by the international standards such as ISO/IEC14443-2, and can precisely process data in response to a modulated signal of either type.
The data transfer methods dealt with by the aforementioned IC card are both based on the common standards, and therefore, files stored in a memory included in the IC card can be managed by using a common OS. In the case where the files stored in the memory are managed by different methods depending upon the data transfer methods, however, the file management cannot be performed by using one OS. Therefore, it is difficult to execute data processing in accordance with different standards in one IC card.
In order to solve this problem, a conventional technique in which a plurality of OSs are included in one IC card so as to activate an appropriate OS identified on the basis of information about an IC card OS included in a command received from an external device has been proposed (for example, see Japanese Laid-Open Patent Publication No. 2003-76954 (pp. 6–7 and FIG. 8)). In this conventional technique, one IC card is applicable to a plurality of OSs (IC card OSs), resulting in realizing what is called a multi-OS IC card.
Although the latter IC card includes a plurality of OSs, it has a problem of slow response to an initial command because an appropriate OS is not found until the initial command is received from an external device. This problem is serious particularly when a sufficient time is necessary for activating an OS. For example, when this IC card is applied to a commuting ticket, it is necessary to complete various data processing through data transfer between the IC card and an automatic ticket gate before a user passes through the ticket gate. However, if the response to an initial command received from the automatic ticket gate is slow, the necessary data processing cannot be completed before the user passes through the automatic ticket gate, and therefore, there may arise a problem that the user cannot pass through the ticket gate.
Furthermore, according to, for example, ISO/IEC14443-3, a time taken by an IC card from receipt of a command to sending of a response is previously defined. Therefore, in the method where an appropriate OS is found after receiving a command, since a time for activating the OS is additionally necessary, a response may not be sent within the defined time.
For the purpose of solving these problems, it can be considered that the time required for activating an OS is reduced by accelerating an operation clock of an LSI built in an IC card. However, the acceleration of the operation clock is not preferred because it may increase power consumption. In particular, power supply is limited in a contactless IC card, and therefore, there arises another problem that a sufficient communication distance performance cannot be exhibited when the power consumption is increased by accelerating the operation clock.